/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.mahout.ga.watchmaker.cd;
import java.util.List;
import java.util.Random;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import org.uncommons.maths.random.Probability;
import org.uncommons.watchmaker.framework.operators.AbstractCrossover;
/**
* Crossover operator.
*/
public class CDCrossover extends AbstractCrossover<CDRule> {
public CDCrossover(int crossoverPoints) {
super(crossoverPoints);
}
public CDCrossover(int crossoverPoints, Probability crossoverProbability) {
super(crossoverPoints, crossoverProbability);
}
@Override
protected List<CDRule> mate(CDRule parent1, CDRule parent2, int numberOfCrossoverPoints, Random rng) {
Preconditions.checkArgument(
parent1.getNbConditions() == parent2.getNbConditions(),
"Cannot perform cross-over with parents of different size.");
CDRule offspring1 = new CDRule(parent1);
CDRule offspring2 = new CDRule(parent2);
// Apply as many cross-overs as required.
for (int i = 0; i < numberOfCrossoverPoints; i++) {
// Cross-over index is always greater than zero and less than
// the length of the parent so that we always pick a point that
// will result in a meaningful cross-over.
int crossoverIndex = 1 + rng.nextInt(parent1.getNbConditions() - 1);
for (int j = 0; j < crossoverIndex; j++) {
swap(offspring1, offspring2, j);
}
}
List<CDRule> result = Lists.newArrayListWithCapacity(2);
result.add(offspring1);
result.add(offspring2);
return result;
}
static void swap(CDRule ind1, CDRule ind2, int index) {
// swap W
double dtemp = ind1.getW(index);
ind1.setW(index, ind2.getW(index));
ind2.setW(index, dtemp);
// swap O
boolean btemp = ind1.getO(index);
ind1.setO(index, ind2.getO(index));
ind2.setO(index, btemp);
// swap V
dtemp = ind1.getV(index);
ind1.setV(index, ind2.getV(index));
ind2.setV(index, dtemp);
}
}